I feel you so much, my friend.  If I had the money to be a perpetual student, I would be one of those people who was just an expert in everything with zero real-world experience.  I don’t really have any advice for you (I mean, unless you’ve never heard of Duolingo, which is a great language-learning system that also has an app and is free, unlike Rosetta Stone), except that it’s completely possible to learn a bunch of miscellaneous crap on your own.  

• The Wikipedia spiral is treacherous, but a good default.  
  
• Get a random book from the library or troll the free books on the internet, buy one if you have the money.  
  
• For languages specifically, Duolingo is fantastic and they have an ever-expanding collection of languages, including colloquialisms.  I’d start with something that’s spoken in your area so that you can get some practice with real people (Spanish is a dominant language in a lot of the US, so that’s a good fallback because it’s also useful).  Google it, make an account, even if you don’t know if you’ll use it.  It’s free, take advantage.

Yep.  That’s pretty much what I got.  If you figure out a way to get to more stuff, or get more hours in the day, please make me the first person you tell, because I would love to have six more hours in the day to get stuff done.